The OGS shipborne gravity measurements began in early 1961. At the very beginning there was a collaboration with the Saclant ASW Research Centre of La Spezia, who forwarded the ship and the navigation control system (first with radar fixes and then with a prototype of Loran C receiver). From 1961 to 1965, eleven cruises were carried out covering a total amount of 60,000 nautical miles of navigation. From 1965 to 1972, OGS operated on ships forwarded by by National Council of Researches (CNR), at first with the R/V Bannock and then, towards the end, with R/V L.F. Marsili. Sea surface gravity measurements were undertaken on more than 300,000 km of profiles with the Askania-GSS2 meter for scientific purposes.